Misconceptions about Immunization

A few physicians have been promoting the idea that the mercury
content of vaccines is a cause of autism and that autistic children
should undergo chelation
therapy to be detoxified. Lawsuits have been filed, and several
attorneys are advertising on the Internet for more clients. The
situation arose because until recently, certain vaccines contained
thimerosal, a mercury-containing preservative that is no longer
used in most of the vaccines now recommended for children. However,
there are several reasons why concerns about the use of thimerosal
in vaccines are misguided:

The amounts of mercury involved were very small.

No link between mercury and autism has been proven. If the thimerosal in vaccines caused mercury poisoning, the symptoms would affect all parts of the nervous system.

Autistic children do not have the movement disorders and peripheral nerve damage that that are characteristic of mercury poisoning.

There is no scientific evidence or logical reason to believe that autism has a toxic
cause.

Thimerosal has been used as preservative in biologics and vaccines
since the 1930s because it prevents bacterial and fungal contamination,
particularly in multidose containers. In 1997, the US Food and Drug Administration Modernization Act mandated identification and quantification of mercury in all food and drugs. The subsequent FDA review noted
that with the increased number of vaccines then recommended for
infants, the total amount of mercury in vaccines containing thimerosal
might exceed the levels recommended by other federal agencies
[1]. The mercury limits imposed by these agencies have a wide
margin of safety; and there was no information suggesting that
any infant had been harmed. Nevertheless, to be super-cautious,
the U.S. Public Health Service (PHS) and the American Academy
of Pediatrics (AAP) asked doctors to minimize exposure to thimerosal-containing
vaccines and manufacturers to remove thimerosal from vaccines
as soon as possible [2].

By mid-2000, thimerosal-free vaccines against hepatitis B and
bacterial meningitis were widely available. A combination vaccine
for diphtheria, pertussis, and tetanus is also available today
without thimerosal. Measles/mumps/rubella (MMR), chickenpox, inactivated
polio, and pneumococcal conjugate vaccines have never contained
thimerosal. Thus, except for some influenza vaccine, none of the
vaccines now used to protect preschool children against 12 infectious
diseases contain thimerosal as a preservative. Certain flu vaccines
and tetanus-diphtheria vaccines (Td) given to children age 7 and
older still contain thimerosal as a preservative.

Before the recent reductions, the maximum cumulative exposure
to mercury via routine childhood vaccinations during the first
six months of life could have been 187.5 micrograms (which averages
to about 1 microgram per day. With the newly formulated vaccines,
the maximum cumulative exposure during the first six months of
life should now total no more than 3 micrograms of mercury [3].
No studies have shown that either the old or the new amounts
have any toxic effect.

The U.S. Centers for Disease Control and Prevention has compared
the incidence of autism with the amount of thimerosal received
from vaccines. Preliminary results indicated no change in autism
rates relative to the amount of thimerosal a child received during
the first six months of life (from 0 micrograms to greater than
160 micrograms). A weak association was found with thimerosal
intake and certain neurodevelopmental disorders (such as attention
deficit hyperactivity disorder) in one study, but was not found
in a subsequent study [4]. Additional studies are planned, but
it is unlikely that any significant association will be found.

An Institute of Medicine (IOM) committee, which issued a comprehensive
report in October 2001, found no proof of a link between thimerosal-containing
vaccines and autism, attention deficit-hyperactivity disorder,
speech or language delays, or other neurodevelopmental disorders
[5].

A study published in 2002 of infants who were 6 months of age
or younger compared the levels of mercury in the blood, hair,
urine, and stool of 40 who received vaccines containing thimerosal
and 20 who received vaccines without thimerosal. The study found:

Mercury levels in blood and urine were low in all infants
studied and in many cases too small to measure. There was no
observed dose-dependent relationship between the level of thimerosal
received through vaccination and the level of mercury in the
body.

Mercury levels in blood did not exceed, at any time, the
blood levels that correspond to Environmental Protection Agency
guidelines for exposure.

Mercury levels in the stool of infants receiving vaccines
containing thimerosal were relatively high compared to mercury
levels in the stool of infants who were not exposed to thimerosal,
providing evidence that mercury from thimerosal is eliminated
in the stool of infants.

Seven studies reported between 2003 and 2006 found no association between exposure to thimerosal in vaccines and the incidence of autism [7].

Thimerosal was eliminated from most vaccines in 2001. If it actually caused autism, the removal would be followed by a sharp drop in the number of newly diagnosed cases. However, in 2007, a study of autism rates in California found that no drop occurred [8]. The data were published in the Archives of General Psychiatry accompanied by an editorial that stated:

Parents of autistic children should be reassured that autism in their child did not occur through immunizations. Their autistic children, and their siblings, should be normally vaccinated, and as there is no evidence of mercury poisoning in autism, they should avoid ineffective and dangerous "treatments" such as chelation therapy for their children [9].

The Bottom Line

The use of chelation therapy to treat autistic children is
completely bogus. Several lawsuits have been filed by parents who were victimized in this way [10].